1. Field of the Invention
The present invention relates generally to digital capture devices, and more particularly, to digital still cameras, digital video cameras, digital video encoders and other media capture devices.
2. Description of the Related Technology
The distinction between still devices and motion devices is becoming blurred as many of these devices can perform both functions, or combine audio capture with still image capture. The capture of digital content is expanding rapidly due to the proliferation of digital still cameras, digital video cameras, and digital television broadcasts. Users of this equipment generally also use digital production and authoring equipment. Storing, retrieving, and manipulating the digital content represent a significant problem in these environments. The use of various forms of metadata (data about the digital content) has emerged as a way to organize the digital content in databases and other storage means such that a specific piece of content may be easily found and used.
Digital media asset management systems (DMMSs) from several vendors are being used to perform the storage and management function in digital production environments. Examples include Cinebase, WebWare, EDS/MediaVault, Thomson Teams, and others. Each of these systems exploit metadata to allow constrained searches for specific digital content. The metadata is generated during a logging process when the digital content is entered into the DMMS. Metadata generally falls into two broad categories:                Collateral metadata: information such as date, time, camera properties, and user labels or annotations, and so forth;        Content-based metadata: information extracted automatically by analyzing the audiovisual signal and extracting properties from it, such as keyframes, speech-to-text, speaker ID, visual properties, face identification/recognition, optical character recognition (OCR), and so forth.        
Products such as the Virage VideoLogger perform the capture and logging of both of these types of metadata. The VideoLogger interfaces with the DMMS to provide the metadata to the storage system for later use in search and retrieval operations. These types of systems can operate with digital or analog sources of audiovisual content.
The capture of digital content offers an opportunity which is not present in analog capture devices. What is desired is a capability to embed a content-based analysis function in the capture device for extracting metadata from the digital signals in real-time as the content is captured. This metadata could then be later exploited by DMMSs and other systems for indexing, searching, browsing, and editing the digital media content. A central benefit of this approach would be that it is most valuable to capture this type of metadata as far “upstream” as possible. This would allow the metadata to be exploited throughout the lifecycle of the content, thereby reducing costs and improving access to and utilization of the content. Such an approach would be in contrast to the current practice of performing a separate logging process at some point in time after the capture of the content. Therefore, it would be desirable to capture the metadata at the point of content capture, and to perform the analysis in real-time by embedding metadata engines inside of the physical capture devices such as digital still cameras, digital audio/video cameras, and other media capture devices.
Some previous efforts at capturing metadata at the point of content capture have focused on the capture of collateral metadata, such as date/time, or user annotations. Examples of these approaches can be found in U.S. Pat. No. 5,335,072 (sensor information attached to photographs), U.S. Pat. No. 4,574,319 (electronic memo for an electronic camera), U.S. Pat. No. 5,633,678 (camera allowing for user categorization of images), U.S. Pat. No. 5,682,458 (camera that records shot data on a magnetic recording area of the film), and U.S. Pat. No. 5,506,644 (camera that records GPS satellite position information on a magnetic recording area of the film). In addition, professional digital cameras being sold today offer certain features for annotating the digital content. An example of this is the Sony DXC-D30 (a Digital Video Cassette camera, or DVC) which has a ClipLink feature for marking video clips within the camera prior to transferring data to an editing station.
Many aspects of digital capture devices are well understood and practiced in the state of the art today. Capture sensors, digital conversion and sampling, compression algorithms, signal levels, filtering, and digital formats are common functions in these devices, and are not the object of the present invention. Much information can be found in the literature on these topics. For example, see Video Demystified by Keith Jack, published by Harris Semiconductor, for an in-depth description of digital composite video, digital component video, MPEG-1 and MPEG-2.